xai-org/grok-build · error · ToolError

User question session ended unexpectedly (coordinator channe

Error message

User question session ended unexpectedly (coordinator channel closed)

What it means

The `ask_user_question` tool sends the question request to the coordinator over a channel; if `sender.0.send(request)` fails (receiver dropped), the coordinator session is gone, so the tool returns a ToolError with this message rather than panicking. Unlike the others this is a proper Err return, surfaced to the model/tool caller.

Source

Thrown at crates/codegen/xai-grok-tools/src/implementations/grok_build/ask_user_question/mod.rs:421

                    "missing_resource",
                    "UserQuestionSender".to_string(),
                ));
            }
        };

        // ── Step 3: Create oneshot ──────────────────────────────────────
        let (result_tx, result_rx) = tokio::sync::oneshot::channel();

        // ── Step 4: Send UserQuestionRequest ────────────────────────────
        let request = types::UserQuestionRequest {
            tool_call_id: ctx.call_id.as_str().to_owned(),
            questions: input.questions.clone(),
            result_tx,
        };

        if sender.0.send(request).is_err() {
            return Err(xai_tool_runtime::ToolError::execution(
                xai_tool_protocol::ToolId::new("ask_user_question").expect("valid"),
                "User question session ended unexpectedly (coordinator channel closed)",
            ));
        }

        // ── Step 5: Emit UserQuestionAsked + read the wait budget ───────
        let params = {
            let questions_json = serde_json::to_value(&input.questions)
                .unwrap_or_else(|_| serde_json::Value::Array(vec![]));
            let res = resources.lock().await;
            if let Some(handle) = res.get::<NotificationHandle>() {
                handle.0.send_user_question_asked(UserQuestionAsked {
                    tool_call_id: ctx.call_id.as_str().to_owned(),
                    questions_json,
                });
            }
            // Shell-injected params win; absent or unset fields keep the legacy
            // env→default budget so non-shell registry consumers are unchanged.
            res.get::<crate::types::resources::Params<AskUserQuestionParams>>()

View on GitHub (pinned to bc7f02eddd)

Solutions

1. Only invoke ask_user_question within an active interactive session with a live coordinator.
2. Check coordinator lifecycle logs for an earlier panic/exit that dropped the receiver.
3. Add a readiness check or keep-alive on the coordinator channel before dispatching questions.
4. Handle the ToolError upstream by skipping the question and continuing with defaults instead of failing the whole turn.

Example fix

// before
if sender.0.send(request).is_err() {
    return Err(..."User question session ended unexpectedly (coordinator channel closed)"...);
}
// after (caller side)
match tool.run(input).await {
    Err(e) if e.to_string().contains("coordinator channel closed") => proceed_with_defaults(input),
    other => other,
}

// check the coordinator channel is still open before asking
if sender.0.is_closed() {
    return proceed_with_defaults(input.questions);
}

match sender.0.send(request) {
    Ok(()) => { /* await response */ }
    Err(_) => {
        tracing::warn!("coordinator gone; skipping user question");
        proceed_with_defaults(input.questions)
    }
}

When it happens

Trigger: The coordinator handling user questions is closed or dropped before/while the tool sends its request — e.g. the interactive session ended, the UI side shut down, or the tool ran outside a live user-question session.

Common situations: Running the ask_user_question tool in a non-interactive/headless context where no coordinator exists; session timeout already torn down the coordinator; a prior error crashed the coordinator task; tool invoked after the user closed the prompt UI.

Related errors

• PTY write channel closed
• failed to build request: {e}
• response parse error: {e}
• ACP response missing result field
• bridge spawn

AI-assisted analysis of xai-org/grok-build@bc7f02eddd (2026-08-31). Data as JSON: /api/errors/a5050830e1c47473. Report an issue: GitHub.